1989 Chevy Cheyenne Intake manifold

If you have it off the engine and looking to clean out all the carbon build up and other gunk. Use brake clean and a wire brush. If your looking to do it on the engine get a quality top engine cleaner. Sea foam is a popular brand. But gm has some really good stuff too. You can draw it into the engine through the vacuum hose at the brake booster. But read all warning labels. Do it outdoors. Nasty smelling stuff.